Carburetor



Oct. 4, 1955 w. su'r o 2,719,519

CARBURETOR Filed Dec. 22, 1950 IN VEN TOR.

05ET Ml JWm/v ATTOENE Y United States Patent C emunnron- Robert W. Suttn,,Elmira,,N. Y;., assignor toBendix Aviatron Corporation, South, Bend, lmL, a corporation of Delaware Application December- 22, 1950, Serial No. 202,286

5 Claims. (Cl..123 -.-122)-.

The-present invention relates to carburetors, for internal combustion engines;

In the operation of internal combustion engines at moderately low and low air temperatures and with the humidity relatively'high, ice sometimes forms onthe car buretor throttle valve and surrounding-throttle bod-y walls and, during idling, may eventually build up until the air supply becomes insufficient to keep the engine running. The formation of ice sometimes occurs at air temperatures well above the freezingpoint' even after the engine has becomefully warm. It is, therefore, one ofthe principal objects of the present invention to provide aearburetor which minimizes the tendency of ice. to form onthethrottle valve and adjacent throttle walls.

Another object of the invention is to provide a means, in combination with a hot air automatic choking device, for preventing the formation of ice on and around the throttle valve of a carburetor.

Another object of the invention is to provide a carburetor construction adapted to apply heat to and around the throttle valve, throttle shaft, and surrounding walls to prevent the formation of ice thereon without causing vaporization or percolation of the fuel in the idle system.

Further objects and advantages will become apparent from the following description and accompanying drawing, wherein a vertical cross-section of a carburetor embodying my invention is shown.

The carburetor shown, except for my improvement, may be considered as a conventional downdraft float-type carburetor having an air horn 10, a choke valve 12 mounted on a choke valve shaft 14, a main body 16, a throttle body 18 and a throttle valve 20 mounted on a throttle shaft 22 which is adapted to be actuated by an accelerating pedal through throttle lever 26 mounted on one end of the throttle shaft.

The main body 16 includes large and small venturis 27 and 28 and a float chamber 30 formed integrally with the main body and containing a float 32 for controlling a fuel inlet valve (not shown). The float chamber is connected with the throat of the small venturi by a main discharge system 34 consisting of perforated tube 36, a main metering jet 38, a discharge nozzle 40, and a vapor vent and air bleed 42. In the operation of the main metering system, fuel flows from the float chamber through metering jet 38 upwardly into a well 43 surrounding tube 36 where it mixes with air from bleed 42 to form a fuel-air emulsion which is discharged through nozzle into the carburetor induction passage. An idle system, including a fuel passage 44, an air bleed 45, and a metering tube 46, connects the main metering system with the induction passage adjacent the throttle valve at ports 47 and 48 above and below the valve. A conventional power enrichment jet and accelerating pump (not shown) are included, and, in the drawing, an actuating mechanism for a mechanical accelerating pump is shown at numeral 49 mounted on an end of the throttle shaft.

An automatic choking device 50 of the hot air type is mounted on air born 10 and, for the purpose of the present description, may be considered a conventional choke control incorporating a coiled bimetallic thermostat 52 and a vacuum actuated piston 54'. The thermostat and piston are enclosed in a housing 56 and are. connected by a pin 58 and lever 60, to choke valve shaft 14. The housing is connected by a tube 61 with a source of hot air such as a stove 62 or the like on or around the exhaust manifoldof the engine 63, and by a conduit 64 with the carburetor induction passage on the engine side of the throttle valve. Conduit 64 is also connected by a passage, shown in part at numeral 65,. to cylinder 66 behind'piston 54.

A bore 67 extends longitudinally through most' of the throttle shaft disposed in the induction passage and is connected at one end to the induction passage below the throttle valve by a passage 68 and at the other end to the vertical portion of conduit, 64 by port 70 and an annular channel '72 around the shaft in communication with the lower end of' the conduit. The outer' end of bore 67 is shown plugged by a rivet or pin 74 adapted to secure the throttle lever to the throttle shaft.

In starting an internalcombustion engine equipped with the carburetor just described, if the engine is cold, the choke valve will be held in its closed position by thermostat 52 to give a rich fuel-air mixture. After the engine begins to fire, the vacuum in the intake manifold and in the carburetor induction passage on the engine side of the throttle valve is transmittedthrough conduit 64, including port 68, bore 67, port 70 and channel 72, to the choke housing 56, and through conduit to cylinder 66 behind piston 54, causing said piston to partially open the choke valve. The manifold vacuum causes air to flow through tube 61 from a stove (for example) on the exhaust manifold of the engine to and through housing 56 and tube 64. Shortly after the engine begins to fire, the exhaust manifold becomes hot, heating the air passing through tube 61 to the housing, which in turn heats thermostat 52, causing the choke valve gradually and continually to open further until it has become fully opened.

On leaving housing 56, the hot air passes through conduit 64 and bore 67, where it heats the throttle shaft 22, throttle valve 20, and the walls of the throttle body adjacent the shaft and valve, and prevents the formation of ice on the throttle body walls and throttle valve. Since the lower end of the idle passage 44 and discharge ports 47 and 48 are at a point on the throttle body walls farthest from the throttle shaft, much of the heat given off by the heated air passing through the shaft is dissipated by the walls and valve before it reaches the idle conduit so that little or no vaporization of the fuel occurs in the idle system.

Modifications may be made in the arrangements of the hot air conduits without departing from the scope of the present invention. For example, in carburetors not equipped with a hot air automatic choke, conduit 64 may be connected directly with the source of hot air. In some installations, it may be desirable to provide independent hot air supply conduits for the choke and the throttle shaft. Further, conduit 64 may be in the form of a separate tube extending between the choke housing and the throttle shaft. In double barrel carburetors, conduit 64 may be connected to bore 67 at one end of a common throttle shaft for throttle valves of both barrels or it may be connected to the shaft between the barrels. In this type of installation a port 68 should be provided for each barrel and the air flow through the ports should be equalized. Since the principal object of the arrangement of the hot air conduits in the throttle body is to heat the throttle shaft which in turn heats the throttle plate without appreciably heating the throttle body adjacent the idle discharge ports, an arrangement in which the conduits pass around one or both ends of the throttle shaft may be "ice used in place of bore 67. Other modifications may be made to suit requirements.

I claim:

1. In an internal combustion engine carburetor having an induction passage with a choke and throttle therein, a shaft for said choke, a shaft for said throttle, a temperature responsive means connected to said choke shaft, a housing around said temperature responsive means, a passage for supplying heated air to said housing, a bore extending longitudinally of said throttle shaft, a conduit connecting said housing with said bore, and a port connecting said bore wtih the induction passage on the engine side of the throttle.

2. In an internal combustion engine carburetor having an induction passage with a choke and throttle therein, a shaft for said choke, a shaft for said throttle, a temperature responsive means connected to said choke shaft, a housing around said temperature responsive means, a passage for supplying heated air to said housing, a bore extending longitudinally of said throttle shaft, a conduit connecting said housing with said bore near one end thereof, and a port connecting the induction passage on the engine side of the throttle with the other end of said bore.

3. In an internal combustion engine carburetor having an induction passage with a choke and throttle therein, a shaft for said choke, a shaft for said throttle, a temperature responsive means and a pressure responsive means connected to said choke shaft, a housing around said temperature responsive means, a passage for supplying heated air to said housing, a bore extending longitudinally of said throttle shaft, a conduit connecting said housing and said pressure responsive means with said bore, and

4 a port connecting said bore with the induction passage on the engine side of the throttle."

4. In an internal combustion engine carburetor having an induction passage with a choke and throttle therein, a shaft for said choke, a shaft for said throttle, a temperature responsive means and a pressure responsive means connected to said choke shaft, a housing around said temperature responsive means, a passage for supplying heated air to said housing, a bore extending longitudinally of said throttle shaft, a conduit connecting said housing and said pressure responsive means with said bore near once end thereof, and a port connecting the induction passage on the engine side of the throttle with the other end of said bore.

5. A carburetor for an internal combustion engine comprising an induction passage, a choke in said passage, a throttle in said passage, a temperature responsive means for controlling said choke, a housing for said means, a shaft for said throttle, an axial bore in said shaft, a conduit connecting said housing with one end of said bore, a passage connecting the other end of said bore with the induction passage, and a passageway for supplying heated air to said housing.

References Cited in the file of this patent UNITED STATES PATENTS 1,886,787 Buraglia Nov. 8, 1932 2,088,464 Chandler et a1 July 27, 1937 2,269,706 Brown Jan. 13, 1942 2,564,114 Kittler Aug. 14, 1951 

